The goal of the Monoclonal Antibody Core Facility is to support the research interests of Memorial Sloan Kettering Cancer Center investigators by providing the following four high quality services not only at a reasonable cost but also in a timely manner. 1) In vitro production of pre-existing monoclonal antibodies (mAbs): This service enables investigators to order cell free conditioned media (bioreactor supernatants) containing 0.5 - 1.5 mg/ml of mAb and ranging from 25 - 55% pure. At this concentration and purity, most mAbs can be used without any further processing for applications such as western blotting, immunoprecipitation, in vivo cell depletions and cell purifications. 2) Purification of mAbs: For experimental techniques that require purified mAb, the facility will purify mAbs from the bioreactor supernatants using conventional chromatographic techniques. 3) Generation of new mAbs: The facility works directly with investigators to generate new mAbs specific for their particular research needs. This service can be broken down into five distinct categories: a) consultation (free of charge), b) immunization of rodents, c) fusion of the spleen(s), d) maintenance of the fusion products and e) subcloning of positive cells. 4) Mycoplasma testing: The facility provides a PCR-based screening service to detect mycoplasma contamination that may be present in the cell lines, media, sera, or other relevant supplements.